let arr = ['1', '1', '2', '3']
function highFrequency(arr) {
    let obj = {}
    let max = 1, res = ''
    arr.forEach(item => {
        if(obj[item]) {
            obj[item]++
            if(obj[item] > max) {
                max = obj[item]
                res = item
            }
        }
        else {
            obj[item] = 1
        }
    })
    return res
}